The
BSD derivatives of Unix were without doubt the mainstream product in
the booming eighties workstation and server industry. While the
commercial market has since embraced SVR4 ostensibly for reasons of
portability, BSD derivatives are still widely in use, and will continue
to be for some time yet. Indeed, the BSD/OS system is an essentially new
product and has found a strong following in its own market niche.

BSD Unix

The early genealogy of BSD Unix was discussed in some detail
in February 1996 OSR. To pick up from that point, DARPA had specified
that BSD become the standard networked operating system for defence
contracting and research sites.

The early to mid eighties were the period during which the
Unix workstation emerged as a product and took the previous minicomputer
marketplace by storm, much to the chagrin of established proprietary
minicomputer vendors. Many have not recovered from the assault, and
essentially remain entrenched in commercial niche markets.

The principal vehicle of the Unix assault on the proprietary
vendors was 4BSD, and its most visible proponent Sun's SunOS, which we
will further discuss. Sun however were not the only party selling 4BSD
based product at the time. Virtually all of the mainstream vendors
ported 4BSD to their workstation and minicomputer products, and those
who stuck to proprietary systems, such as Apollo, suffered the ultimate
penalty as a result.

The decline of BSD Unix as a mainstream commercial product
began in the late eighties and early nineties, and it is reasonable to
say that Sun's defection from the BSD camp to the AT&T SVR4 camp was
the decisive move which ultimately dried out the R&D funding for
Berkeley's CSRG lab. With the dissolution of CSRG in the early nineties
the focal point for the development of the standard reference version
of the 4BSD collapsed. For fans for BSD Unix, this was a sad time.

The members of the CSRG development team scattered across the
industry, with the highest concentration ending up with the Colorado
based BSDI, who have continued the development of the final CSRG 4.4BSD
release. At this time BSDI have in effect supplanted CSRG as the core
development group for BSD based commercial product.

4BSD is still in very wide use primarily due the established
base of older SunOS systems, particularly in academia. Because 4BSD was
designed to squeeze every ounce of CPU performance out of its host
platform, it performs better than SVR4 on the same machine (and vendors
who may dispute this do not have a case). Owners of large numbers of
older Sun machines have often been reluctant to move over to Solaris
2/SVR4 as this would cost them both in performance on older machines,
and in the loss of the bundled development tools. The C compiler is
usually unbundled in SVR4 systems (a pleasure for salespeople and a
displeasure for users).

The future of 4BSD lies in BSDI's commercial 4.4 Lite product
(DEC's OSF/1 owing its origins as much to Mach 2.5), and the ever
growing FreeBSD community. The 4BSD operating system still provides much
better networking performance than SVR4 and hosted on the humble PC,
has found a niche market in the Internet Service Provider community.

Sun Microsystems SunOS

The SunOS operating system was the most commonly used 4BSD
derivative during the eighties and nineties, and much of its early
success derived from its philosophy of providing a relatively standard
4BSD product at the programming interface, with a generous provision of
tools for "do it yourself" support. Not only was the C compiler bundled
in, but so were debuggers, disk formatting tools and a fairly
comprehensive suite of user level hardware diagnostics (sundiag).

What this meant is that third party peripherals could be very
easily integrated with the manufacturer's basic product, indeed the boom
in the third party integrator's industry had much to do with this kind
of support.

The final mainstream release of SunOS was 4.1.3, which has
recently been followed by 4.1.4 which is essentially the 4.1.3 kernel
with an accumulation of various bug fixes added in. This includes the
motherboard serial port driver rewrite.

Beneath the system call interface SunOS is essentially a
unique animal, with a large number of Sun specific features against the
CSRG 4.2 and later 4.3 releases. The most notable difference lies in the
device driver interface, which is essentially proprietary to Sun.

The history behind the device driver interface is quite
interesting, and can be traced back to the original SPARCstation 1
machine, which was Sun's first RISC workstation. Until then, the SunOS 3
operating system used the standard Berkeley driver model, where the
kernel executed a probe call to find a
physical device such as an I/O board or a disk drive, and once it had
found the device, it would then execute an attach call to make the
device visible to the operating system.

The radicals in Sun's software development group thought that
this could be improved upon, and proposed what they intended to become
a new industry standard in device driver interfaces. This was to become
the Open Boot PROM (OBP). The central idea behind OBP was to provide an
intelligent boot-PROM on the machine, which would do all of the probing
instead of the operating system. This meant that most of the platform
specific code, particularly in workstations, would migrate from the
operating system into the by default platform specific boot-PROM.
Instead of having the kernel call probe, it called a new program,
identify, which read a table in memory which contained all of the
device information. The table was generated at boot time by the OBP
code.

The OBP contained a number of other clever features primarily
aimed at supporting hardware development. One was a Forth language
command interpreter, which is the user interface at the boot prompt
(the ok prompt). This interpreter is supplemented by a toolkit, which
allows manual manipulation of hardware at the register level, as well
as the loading of the OS and insertion of breakpoints into the OS.
Moreover, Sbus I/O cards contained their own boot-PROMs, with embedded
tokenised binary Forth code which was used to provide card specific
initialisation and where applicable, support for booting. It is not
unfair to say that the OBP is technically more sophisticated, powerful
and elegant than the MS-DOS operating system.

The OBP was shunned by other vendors, and ended up becoming a
feature specific to the Sun marketplace. It is used by Sun and by
manufacturers of Sbus I/O cards specific to Sun machines. The now
defunct Solbourne, a Colorado based manufacturer of compatible
machines, did not use the OBP in their Sbus based machine, and this did
indeed create much pain for parties intending to fit these machines
with third party I/O cards. The rise and fall of Solbourne is a story
within itself.

In most other areas, such as the filesystem, virtual memory
system, networking code and other kernel internals Sun provided the BSD
standard interface, but very often reworked the internals. An example
would be the X server implementation, which employed many bits and
pieces from the NEWS windowing scheme. Sun's early and proprietary
windowing tools were retained concurrently with the X based OpenWindows
suite.

Other additions to the operating system, such as the
RPC/XDR/NFS suite, memory mapping of files, and the vnode mechanism,
were home grown and of sufficient importance that they became industry
standards and eventually merged into AT&T SVR4.

The SunOS system will continue to be supported on older Sun
machines, but it is well and truly past its prime as the trail-blazer
of technology in the commercial Unix marketplace.

BSD/OS

BSDI's BSD/OS, formerly known as BSD/386, is the current
incarnation of commercial 4BSD Unix. Of all the commercial Unix
derivatives available, it is the most open by virtue of being available
with a full source tree at an accessible cost in 3 figure numbers
(unlike the AT&T product which used to be available to interested
parties for a 6 figure amount).

Historically BSD/OS shares its early origins with FreeBSD and
NetBSD, but unlike the latter which are maintained by enthusiasts in
the public domain, BSD/OS was further developed commercially by BSDI,
using a team of programmers many of whom previously worked for CSRG.

The first release of BSD/386 hit the market early in 1992, but
its penetration was slowed by the then ongoing litigation by USL. With
the release of the wholly USL free 4.4BSD Lite (the term a distinct
Americanism derived from "Miller's Lite" beer marketing), BSDI produced
the 2.X release of the system which is now the current product.

BSD/OS is a fully featured 4.4BSD Lite system, with a number
of additions merged in from the earlier 4.3/4.4BSD Release 1 product.
The system provides fully compliant POSIX 1003.1 system calls, both
TCP/IP and OSI stack networking support, an implementation of NFS, X11,
troff and TeX, and a bundled C and C++ compiler. The system includes a
bundled commercial Xinside X11 server binary release, but will also
support the public domain XFree86 server.

BSDI have added in a considerable number of enhancements to
the basic 4.4 Lite tree. These include:

People will have an inevitable tendency to compare BSD/OS with
FreeBSD, since they are the only widely available 4.4BSD ports. Whilst
both share the same origins, BSD/OS is a more mature commercially
supported product, with an arguably much larger set of enhancements.
BSDI have concentrated on the Intel platform, and focussed on the ISP
marketplace. Given the superior networking performance of the BSD
design and low cost of PC hardware, this yields a very good return in
"bang for buck". The availability of cheap source code has provided
BSDI with a considerable advantage in the technical customer base, and
the company has held its ground very well against the rush of major
vendors to get a slice of the ISP market. Moreover since BSDI are only
concerned with the operating system, unlike the major vendors whose
agenda by definition must include hardware sales, they can concentrate
on system issues to the exclusion of hardware.

It will be interesting to see BSDI's progress in the longer
term, in what is an inherently volatile and fickle marketplace. If past
experience is any indication, they will be here to stay.